1. Field of the Invention
This invention relates to surgical suturing and, more particularly, to an apparatus that facilitates the cinching of a knot in the suture, as from externally of a cavity in which a laparoscopic procedure is performed. The invention is also directed to a method of cinching a knot utilizing the apparatus.
2. Background Art
Suturing tissue in an open body cavity is a relatively tedious and delicate procedure. This is due principally to the thinness of the suturing thread as well as its tendency to twist about its length. In a normal suturing procedure, the thread is directed through a tissue and the free ends thereof are wrapped to define a half-hitch knot that froths a closed loop, the diameter of which can be reduced ultimately to the point that the thread is cinched at the tissue. As twisting of the thread occurs, restriction of the loop is inhibited, possibly to the point that it is impossible to cinch the knot at the body tissue, as required. Even after one half-hitch knot is formed and properly cinched, the twisting problem persists and may interfere with, or prevent, the subsequent formation of additional half-hitch knots as would "lock" the suture. When this occurs, the surgeon may be required to cut the suture and re-start the process. This process is by nature time consuming. These problems increase the overall time of the operation and contribute undesirably to hand, and overall, surgeon fatigue.
It is known to suture during laparoscopy internally of a cavity. The problems attendant the conventional open procedure described above are present. In fact, these problems are aggravated by reason of having to handle the suturing thread almost completely through the use of elongate instruments. The surgeon is required to extend at least two instruments into the operative cavity and to watch the procedure through a monitor that employs optical fibers extended into the cavity. This type of suturing process may be time consuming and frustrating to the surgeon, particularly in those instances when partially, or improperly formed sutures, must be cut and removed from the cavity.
To effect removal of an improperly tied suture, the surgeon is generally required to direct a separate instrument into the cavity through a cannula. This instrument may be either one that permits grasping of the suture to effect untying thereof, such as a forceps, or a cutting instrument. The use of a forceps to untie a fully or partially formed knot is inconvenient. It is difficult to grasp and hold the thread at a desired location to effect manipulation thereof. This is a particularly difficult task with a tangled or twisted thread.
It is also known to form a half-hitch knot on a suture from a location externally of the tissue. This method, known as extra-corporeal suturing, involves the step of directing a suture carrying needle through a cannula, through internal body tissue, and out the proximal end of the cannula so that the free ends of the suturing thread are accessible from externally of the cavity. The surgeon then manipulates the free ends of the suturing thread by wrapping the threads in such a manner as to define a half-hitch knot. An elongate "pusher" rod, with a bifurcated free end, is engaged with one of the free ends of the thread in the vicinity of where they are wrapped and pressed through the cannula, while at the same time holding both free thread ends projecting away from the loop. As this takes place, the loop diameter restricts to the point that it is ultimately cinched at the tissue.
This procedure is convenient from the standpoint that the half-hitch knots can be formed from externally of the body cavity. However, this introduces other complications. The problem of thread tangling persists. Further, the procedure is inherently awkward by requiring that the free ends of the suture projecting away from the loop be held taut as a pusher is pressed through the cannula to reduce the loop diameter. Thus, there are three manipulation points - the two free ends of the thread projecting away from the loop must be held and one of the threads at the wrapped portion of the loop must be pressed through the cannula. The result is that the procedure may require two sets of hands.
Further, the thread is prone to escaping from the open free end of the pusher. When this occurs, the surgeon is required to attempt to reposition the thread in the pusher end. This is a difficult and time consuming procedure that may be made impossible by twisting of the thread that occurs within the cavity. The end result of this may be that the surgeon may be required to remove the partially locked suture and re-start the procedure.
Further, since the thread is prone to twisting, the thread may bind as the loop diameter is restricted. Excessive pressure exerted by the pusher on the thread with this condition may result in thread breakage.